The Program in Cancer Etiology, Prevention, and Control is focused upon decreasing the burden of cancer in society through improved understanding of cancer's causes and reducing cancer incidence and morbidity. The program includes both a top-down and a bottom-up approach to reducing cancer incidence and morbidity. The top-down approach includes population-based studies to identify causes of cancer in the population and to change behavior known to increase the risk of cancer through social marketing and other approaches. The bottom-up approach includes the identification of carcinogen mechanisms of action, including genomic and proteomic impacts of exposure (primarily repair and metabolism). The interaction of these two approaches provides a powerful program for identification of cancer's causes in the population- based approaches to cancer etiology and laboratory-based scientists focused on identifying the mechanisms of action and impact of exposures on repair and metabolism. The population-based programs are based primarily in the Department of Epidemiology and Preventive Medicine and the California Department of Health Services. Studies of mechanisms of action and impact of exposures are based primarily at Lawrence Livermore National Laboratory and UC Davis. LLNL brings unique technologies (e.g. AMS, genomics and proteomics) to this Program. UC Davis brings substantial expertise in the basic biology of nutrition and nutrient metabolism in both animals and humans to the collaboration, and through its relationship with the Western Center for Human Nutrition Research (USDA) and its clinical resources it offers the infrastructure for clinical as well as epidemiological studies This program will focus on three agents or categories of agents for its application of etiology, prevention and control efforts. These areas are tobacco, nutrition and environmental exposure. Together these agents represent the majority of recognized external causes of cancer, and the greatest opportunity for effective cancer prevention.